There are several arrangements known in the art for establishing a conference call between three or more parties. One method for establishing a conference call involves having a person call each party to the conference and individually bridge each called party onto the conference call. While several people can be added to a single call in a straightforward manner, this technique is limited in the number of parties that can be added to a call without degrading the quality of the telephone service. A straightforward bridging of several calls reduces the amount of power which can be transmitted to any party. Also, this technique requires that the party establishing the conference call ("the host") individually call each participant. This is time-consuming and requires that the host have available each time the conference call is to be set up, the telephone numbers of each of the participants.
A second technique for establishing a conference call involves providing a "dial-in" telephone number, which is accessed through the use of an access code, to join all parties at a common bridge. This technique provides significantly improved performance and auditory quality for conference calls involving a large number of participants. Also, each participant dials in to the bridge, eliminating the need for the host to dial each participant individually. Nevertheless this technique requires that the conference call be prearranged so that a dial-in number and access code can be assigned for the call. Each participant must know of the call beforehand to be able to participate.